James Lee Dimaggio (from left), 40, Ethan Anderson, 8, and Hannah Anderson, 16, whose mother, Christina Anderson, 44, was one of two people found dead in a house fire Sunday night. An Amber Alert was in effect early Tuesday Aug. 6,2013 for the two missing children of Christina Anderson, whose body was found inside a burned rural house near the U.S.-Mexico border, and authorities said Dimaggio, suspected of killing the woman may have abducted the children. (ASSOCIATED PRESS / San Diego Sheriff's Department )

LAKESIDE, Calif. (AP) — A man suspected of abducting a 16-year-old girl after setting his house ablaze with the girl’s mother and possibly her younger brother inside may have booby-trapped his car with homemade explosives, police said Thursday as a search expanded to four states, Mexico and Canada.

Meanwhile, police said an “unusual infatuation” with the teenager might have driven suspect James Lee DiMaggio, 40, to flee with her from his burned home on the California-Mexico border.

“That is kind of a working theory, that it may be something of a motivator,” San Diego County Sheriff’s Capt. Duncan Fraser said. “It’s definitely something that we’re looking at.”

Evidence found in the rubble of the home suggested that DiMaggio may have fled with explosives, Fraser said, declining to elaborate on what was discovered. Investigators worried that DiMaggio might abandon his blue Nissan Versa after rigging it to explode.

“In the event that someone comes across the car, they need to use caution,” Fraser said.

On Sunday night, authorities found the body of 44-year-old Christina Anderson when they extinguished flames at DiMaggio’s rural home. A child’s body also was discovered as they sifted through rubble in Boulevard, a tiny town 65 miles east of San Diego.

The body may be that of 8-year-old Ethan Anderson. Fraser said it could take several days to identify the badly burned remains. Investigators were unable to extract DNA.

DiMaggio told 16-year-old Hannah Anderson a couple months ago he had a crush on her and would date her if they were the same age, said Marissa Chavez, 15, a friend who witnessed the remarks when DiMaggio was driving them home from a gymnastics competition.

“She was a little creeped out by it. She didn’t want to be alone with him,” Chavez said.

DiMaggio is wanted on suspicion of murder and arson in a search that began in California and spread to Oregon, Washington, Nevada, British Columbia and Mexico’s Baja California state. An additional eight FBI agents were assigned to a command post at San Diego sheriff’s headquarters, as state and local law enforcement agencies were on alert.

Oregon State Police fielded more than 130 tips after authorities issued an Amber Alert for DiMaggio and his car with California license plates. A possible sighting was reported in northeast California near Alturas Wednesday afternoon, followed by another about 50 miles along the same highway near Lakeview, in south-central Oregon.

Fraser, whose office had hundreds of leads on DiMaggio’s whereabouts, said the Oregon tip appeared “very credible”

“We’re taking it very seriously,” he said.

Washington State Patrol responded to reports of sightings on Interstate 5, including the Tacoma area, Vancouver and at least one near Bremerton, said Sgt. Jason Hicks.

Messages seeking DiMaggio and the Anderson children appeared on digital billboards and freeway signs throughout the West, said Bob Hoever, director of special programs for the National Center for Missing & Exploited Children. Loud tones beeped on mobile phones in areas covered by the Amber Alerts.

In Mexico, airports, bus and taxi companies and law enforcement agencies were on the lookout, said Alfredo Arenas, international liaison for the Baja California state police.

“This is a pretty much an all-hands-on-deck effort. It’s huge,” Fraser said.

DiMaggio, a telecommunications technician at The Scripps Research Institute, was like an uncle to Hannah and Ethan Anderson. He was close to their parents for years.

Dawn MacNabb, whose son, Alan, was close friends with Hannah, said Hannah told her son Friday that the Andersons were going to visit DiMaggio at his house before he moved.

“She told him Jim was depressed, that it was his last weekend,” MacNabb.

Christina Anderson’s father, Christopher Saincome, said his daughter visited DiMaggio’s home to say goodbye before he moved to Texas.

MacNabb said DiMaggio occasionally took Hannah and her friends to his home and that she felt uncomfortable enough to warn Christina Anderson.